2) Fuel pump relay failures (around 65-70K miles) 1 case where relay failed
open. No fuel. 1 case where relay failed closed. In this case the symptom
first showed as engine dieseling in hot weather. The relay was sticking at
first staying on for up to 10 to 15 seconds after turning of the ignition.
Our local dealership could not find the problem. You can listen for the
problem. Finally, the relay failed closed, with no dieseling effect. This
drained the battery and left it dead. Again, the local shop could not
figure it out. They simply said the battery died. I had told them that I
heard a clicking sound from near the fuse box behind the battery.

Further Comments and an Emergency Fix

I had/have same problem with truck dieseling as described which is
advertises an obvious problem (but what; took awhile) and the battery drain
which is the silent killer. The tip off is if you can still hear the fuel
pump by the time your feet hit the ground upon a normal exiting of the
vehicle, there's a good chance your relay is sticking. The following
procedure is not a fix (get a new relay), but might help if you're on a
camping trip, or don't have time to change it. Under the hood, on the
battery side (for my 91 anyway) find the fuse for the fuel pump relay. If
you are truly having the problem described you can make the relay open and
close by removing/replacing the fuse, or by connecting/disconnecting the
battery because even with the engine off, there is still power to the relay
which is cute, BUT IT'S WRONG! (stealing that quote from some cartoon, but
I can't remember which one). Anyway, directly underneath the fuse is the
relay. Wiggle it, fondle it, move it, play with it whatever you want to do
with it in the privacy of your own garage, but seriously, that seems to
help fix it for awhile. I suppose for safety you should disconnect the
battery but I never do. If you're wondering why I haven't bought a new
fuse it's simple. I'm too lazy, and will get to it soon.

A Possible Solution Contributed by Patrick McClanahan

I found that there is a series of wiring that goes from the drivers side
firewall across the front of the engine block and around to the passenger
side firewall and to the inside to an inertia switch (the switch under the
carpet at the front of the inside firewall). The wiring in front of the
block in the shielding developes a short causing the relay to short and
snap the inertia switch constantly making you think that the fuel pump is
going out or losing control of the guage and possibly tripping the inertia
switch constantly. The solution is to rewire the harness at those points or
just buy a new wiring harness from a Ford dealer for around $140. If you
choose to buy this harness it will save a little headache on yourself as
all it is a "plug and Play" vs. a wiring and soldering situation for those
not into wiring! Hope this works!